/Engine/Plugins/Experimental/GeometryScripting/Source/GeometryScriptingCore/Public/GeometryScript/MeshNormalsFunctions.h
Flip/Invert the normal vectors of TargetMesh by multiplying them by -1, as well as reversing the mesh triangle orientations, ie triangle (a,b,c) becomes (b,a,c)
static [UDynamicMesh](API\Runtime\GeometryFramework\UDynamicMesh) * FlipNormals ( [UDynamicMesh](API\Runtime\GeometryFramework\UDynamicMesh) * TargetMesh, [UGeometryScriptDebug](API\Plugins\GeometryScriptingCore\GeometryScript\UGeometryScriptDebug) * Debug )